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Some major model changes were made to the IFS with the introduction of Cy49r1 in October 2024.  These are:

• Medium range ensemblem range ensemble  ensemble forecast system:
  • HRES and Ensemble Control are are scientifically, structurally and computationally identical.  HRES output is maintained for the convenience of users but will be withdrawn in a future update cycle.
  • Unchanged are: 
    • the horizontal resolution remains at 9 Km.
    • the vertical resolution remains at 137 model levels. 
    • the number of ensemble members remains at 50 members plus the control member.
    • the medium range ensembles are run daily Day0 to Day15 based on 00UTC and 12UTC data and Day-0 to Day6 based on 06UTC and 18UTC data.

• Sub-seasonal range ensemble (formerly extended range) forecast system:
  • The name of the extended range ensemble and associated forecast period is changed to sub-seasonal range ensemble and forecast period.  The forecast system itself is unchanged.
  • Unchanged are: 
    • the horizontal resolution remains at 36 km.
    • the vertical resolution remains at 137 model levels.
    • the number of ensemble members is 100 members plus a control member.
    • the sun-seasonal range ensemble is run daily from Day0 to Day46 based on 00UTC data.

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